Share Count Common Shares Underlying – all classes Common Shares – all classes, net of assumed repurchase at $18/share Category (000’s) (000’s) Notes Total shares issued to Billtrust, excluding options 94,764 94,764 Shares held by pre-Business Combination Billtrust equityholders, Class 1 (Voting) and Class 2 (Non-voting) SPAC public shareholders 24,998 24,998 Shares previously held by SPAC shareholders PIPE shares 20,000 20,000 Issued to PIPE investors in connection with the Business Combination Sponsor shares 3,125 3,125 Not subject to forfeiture, not in escrow Sponsor Vesting Shares 2,375 2,375 SPAC sponsor shares issued, but subject to lock up and vesting based upon achievement of the $12.50 and $15.00 price milestones, which were achieved as of February 10, 2021 Billtrust Earnout Securities 12,000 12,000 100% performance based with 50% vesting based on an average share price of $12.50 and 50% vesting based on an average share price of $15.00 in 20 of 30 business days. This condition was achieved on February 10, 2021. Sub-total 157,262 157,262 Warrants outstanding (public shareholders) 12,500 4,514 Callable for $0.01 per warrant if closing price of BTRS Holdings is greater than or equal to $18.00 for any 20 trading days during any 30 day trading period Number of underlying shares calculated based on treasury stock method, assuming $18 share price Each warrant is exercisable for one share at an exercise price of $11.50 12,500 warrants outstanding Billtrust carryover options 15,180 12,439 Number of underlying shares converted based on treasury stock method at $18 15,180 options outstanding, vested and unvested carried over from pre-merger. Vesting is generally time based every 6 months over a two year or four-year period, except for a limited number of options that have immediate vesting. Unvested options granted in January 2021 7,637 507 Number of underlying shares converted based on treasury stock method at $18 Options granted to employees on January 12, 2021 under the new 2020 Equity Incentive Plan, at an exercise price of $16.80, vesting equally every 6 months over a 4 year period. Fully diluted share count 174,722 1 Option and share data as of closing date of January 12, 2021 (1)